> Here's a beginner's question, I did quite a bit of experimenting and > searching but could not find the solution yet. > > The scenario: every time motion is detected in a room, the date+time is > recorded. > I would like to store+visualize this data using rrdtool.
Indeed a beginner's question. You are trying to hammer a nail using a screwdriver. Maybe it will work but you would do better if you'd use the right tool for the job. RRDtool is great in storing and graphing rates over time. But that is not what you are trying to do. This is probably why you are unable to find examples. > Thanks in advance for any suggestions! Accept that RRDtool works with rates. Work from there, or select another tool. "Work from there": for instance: record each activity as "one per second", "during one second". Then graph 604800 seconds together, multiply the rate by 604800 and display the average. That should be the number of events per week. Updating as one per second during one second involves two updates: zero at the second before the event, time n-1, and one at the event time itself, time n. Thus you need to make another choice: do I just update at "n-1" and ignore error messages from rrdtool in the case there happen to be 2 events in a row, or you do keep track (outside rrdtool) of it. Hmm... and what if there are two events in the same second? For instance at hh:mm:ss:51 and at hh:mm:(ss+1):49 ? Or, without rounding, at hh:mm:ss:00 and at hh:mm:ss:59 ? Trying to show how much events happen during each day of the week, during e.g. a year, involves in an extra hack of showing one week on the X-axis of RRDtool, but showing data for 52 weeks (or 53). It can probably be done. That does not mean you should try. "select another tool": i have no suggestions on ready to use programs. Look for them, or roll your own. Use one of the available "normal" databases, and a separate graphing program. With some clever db design you will be able to achieve what you want, with only a few selects at graph time, and an insert at event time. Even if you have to build everything yourself from scratch, you will need less time and effort in the end. Maybe others will not agree with me, and maybe I am too pessimistic, or maybe I did not quite understand all you are trying to do. Everybody feel free to voice your opinion. \Back to vacation mode now! Cheers, Alex _______________________________________________ rrd-users mailing list rrd-users@lists.oetiker.ch https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users